The application generally relates to an electromagnetic compatibility (EMC) filter. The application relates more specifically to an electromagnetic compatibility filter for use in variable speed drives (VSD).
A variable speed drive (VSD) for heating, ventilation, air-conditioning and refrigeration (HVAC&R) applications typically includes a rectifier or converter, a DC link, and an inverter. VSDs that incorporate active converter technology to provide power factor correction and reduced input current harmonics also generate a significantly higher level of common mode RMS and peak to peak voltage to the motor stator windings as compared to conventional VSDs.
The VSD generates a common mode noise with respect to ground that can cause interference with radio equipment and transmissions. To reduce or eliminate noise generated by the VSD it is necessary to suppress the common mode noise by giving it a circulating path within the VSD. This filter creates a small loop area for the common mode noise there by reducing the interference.
Typically EMC filters are used in conjunction with VSDs to reduce the transfer of electromagnetic noise between the VSD and mains power supply. The EMC filter comprises a large inductor which is connected in series with the VSD input. Such EMC filters reduce the overall efficiency of the VSD due to magnetic losses, and further increase the cost and size of the VSD.
Other features and advantages will be made apparent from the present specification. The teachings disclosed extend to those embodiments that fall within the scope of the claims, regardless of whether they accomplish one or more of the aforementioned needs.